/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect.testing.testers;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.testing.Helpers;

import java.lang.reflect.Method;

import org.junit.Ignore;

/**
 * Tests {@link java.util.List#hashCode}.
 *
 * @author George van den Driessche
 */
@GwtCompatible(emulated = true)
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
public class ListHashCodeTester<E> extends AbstractListTester<E>
{
    public void testHashCode()
    {
        int expectedHashCode = 1;
        for (E element : getOrderedElements())
        {
            expectedHashCode = 31 * expectedHashCode + ((element == null) ? 0 : element.hashCode());
        }
        assertEquals(
                "A List's hashCode() should be computed from those of its elements.",
                expectedHashCode,
                getList().hashCode());
    }

    /**
     * Returns the {@link Method} instance for {@link #testHashCode()} so that list tests on
     * unhashable objects can suppress it with {@code FeatureSpecificTestSuiteBuilder.suppressing()}.
     */
    @GwtIncompatible // reflection
    public static Method getHashCodeMethod()
    {
        return Helpers.getMethod(ListHashCodeTester.class, "testHashCode");
    }
}
